This document is an overview of the recommended guidelines for connecting to Mercury™ SmartPrecision™ programmable interpolators. It will allow users to design connections which will ensure the best quality and most reliable encoder performance.
The Mercury Series SmartPrecision™ interpolator design is based on a Field Programmable Gate Array or FPGA. The FPGA must be loaded with “code” each time the device is powered on. The code resides in a non-volatile memory device external to the FPGA called a Serial Flash chip. On each power-up, a micro-controller on the interpolator loads the code from the Serial Flash device into the FPGA
This code is originally loaded at the factory using “Reserved” pins on the interpolator’s HD15 connector. If noise is induced on one of these pins, a “false” download command may be interpreted. As a result, data in the Serial Flash chip can be corrupted. This data corruption will prevent the FPGA from being loaded properly at power-up and will interfere with the interpolator’s normal function. Units that have been corrupted in this fashion can be reprogrammed in the factory and returned to normal operation.
To prevent any issues with data corruption, follow these recommendations for connecting to the SS200c, SS300c, and SS350c SmartPrecisionTM interpolators with quadrature output or the SS300cSi and SS350cSi interpolators with SPI serial outputs.
- Consult the applicable interface drawing or datasheet available on the Celera Motion website
- Wire up the power, ground, and other signal pins as per the pin map diagrams shown below in Tables 1, 2or 3 below depending on your applicable interpolator model.
- Pins 2 and 3 are receive and transmit lines for RS232 communication to SmartPrecisionTM software. They should only be connected to for this purpose.
- Pins labeled as “Reserved” should not be connected to for any reason.
- Pin 1 is a test pin used only for factory programming. Tie this pin to ground (pin 13) in your mating HD15connector as displayed in Figure 1 below.